• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.343-348
• /
• 1999

The purpose of this study is to evaluated the effects of added expanded polystyrene on the basic properties of UP mortar. Polyester resin mortars are prepared with expanded polystyrene ratio in styrene monomer (EPS/PS), and the ratio of total polystyrene resin to UP resin (PS/UP). And it is tested for viscosity of UP resin added PS resin, slump-flow test, working life, flexural and compressive strengths, and curing shrinkage test. From the test result, Viscosity of resin for polymer mortar increases with increasing PS content. Curing shrinkage of UP mortar is considerably smaller than that of plain UP mortar, nevertheless, reduction in the strengths is not recognized according to adding PS resin. In this study, we can obtain the optimum mix proportions of polymer mortar using PS resin.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.6
• /
• pp.160-166
• /
• 2004

In this study, a new algorithm, named as Contour Offset Algorithm(COA) is developed to fabricate precise features or patterns in the range of several micrometers by nano replication printing(nRP) process. In the nRP process, a femto-second laser is scanned on a photosensitive monomer resin in order to induce polymerization of the liquid monomer according to a voxel matrix which is transformed from the bitmap format file. After polymerization, a droplet of ethanol is dropped to remove the unnecessary remaining liquid resin and then only the polymerized figures with nano-scaled precision are remaining on the glass plate. To obtain more precise replicated features, the contour lines in voxel matrix should be modified considering a voxel size. In this study, the efficiency of the proposed method is shown through two examples in view of accuracy.

• Magazine of the Korea Concrete Institute
• /
• v.5 no.4
• /
• pp.156-166
• /
• 1993

The results of an experimental study on the manufacture and the mechanical properties of steel fiber reinforced polyester resin composites utilizing industrial waste products(fly ash) are presented in this paper. The composites using steel fiber, fly ash, unsaturated polyester resin, styrene monomer, catalyst (cobalt octate) and accelerator(methyl ethyl ketone peroxide), fine and coarse aggreates were prepared using various mixing conditions. As the test results show. the mechanical and physical properties, such as the compressive, tensile and flexural strengths, and the setting shrinkage of fly ash$\cdot$polyester resin composites were improved considerably by increasing the fly ash-binder ratio. And the workability of steel fiber reinforced fly ash$\cdot$polyester resin composites was reduced with increasing the fly ash-binder ratio and steel fiber content. Also, the compressive, flexural strength and toughness of the composites were remarkably increased by increasing steel fiber content.

• Journal of the Korean Applied Science and Technology
• /
• v.28 no.1
• /
• pp.35-47
• /
• 2011

For the synthesis of water soluble acrylic modified epoxyester resin, fatty acid/epoxy ratio of 50/50 was used, and introduced maleic anhydride. Ratio of styrene/acrylic acid of acrylic monomers was fixed 85/15 and ratio of epoxyester/acrylic monomer was controlled 80/20, 75/25, 70/30, 65/35, and degree of neutralization were changed 65%, 80%, to 100%. As a result, 40% solids acrylic modified epoxyester resins were synthesized. Resins were evaluated water soluble stability, drying time, water resistant, storage stability and physical properties. And the white paints were prepared, and were evaluated viscosity, drying time, water resistance, adhesion, sagging, spray workability, gloss, salt spray resistance, skinning, whiteness and flash rust. As a result, the degree of neutralization of 100% and the ratio of epoxyester/acrylic monomer of 75/25 showed the best properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.228-229
• /
• 2006

본 연구에서는 PCB에 적용하기 위한 폴리머 타입 후막저항의 하나로서, 포토공정으로 저항 패턴의 형성이 가능한 페이스트를 제조하였다. 기존의 폴리머 후막저항은 스크린 인쇄를 패터닝의 주요 방법으로 하고 있어 패턴의 정밀성이 떨어지는 단점이 있었다. 이를 개선하여 고정밀 저항 패턴의 형성이 가능하도록 Photoimageable Resin을 저항 페이스트의 개발에 도입하였다. Acrylated oligomer 및 monomer, 그리고 Novolac Epoxy를 주 기지상 재료로서 사용하였으며, acrylate와 epoxy의 함량비에 따른 저항 페이스트의 현상성 및 시트저항을 평가하였다. 전도성 Filler 재료로 카본블랙을 이용하였는데, 그 물리적 특성차와 함량이 저항 페이스트의 현상성과 저항값에 미치는 영향을 평가하였다. 실험결과 Acrylate와 epoxy의 비가 2.5:1일 때 현상성이 가장 양호하였으며, 이 조성에 XC72R 카본블랙을 2g 첨가하였을 때 시트저항의 평균값은 약 $6\;k{\Omega}\{\square}$였다.

• Restorative Dentistry and Endodontics
• /
• v.29 no.6
• /
• pp.520-531
• /
• 2004

The aim of this study was to investigate the effect of monomer and filler compositions on the rheological properties related to the handling characteristics of resin composites. Methods. Resin matrices that Bis-GMA as base monomer was blended with TEGDMA as diluent at various ratio were mixed with the Barium glass (0.7 um and 1.0 um), 0.04 um fumed silica and 0.5 um round silica. All used fillers were silane treated. In order to vary the viscosity of experimental composites, the type and content of incorporated fillers were changed, Using a rheometer, a steady shear test and a dynamic oscillatory shear test were used to evaluate the viscosity ($\eta$) of resin matrix, and the storage shear modulus (G'), the loss shear modulus (G"), the loss tangent ($tan{\delta}$) and the complex viscosity (${\eta}^*$) ofthe composites as a function of frequency ${\omega}{\;}={\;}0.1-100{\;}rad/s$. To investigate the effect of temperature on the viscosity of composites, a temperature sweep test was also undertaken. Results. Resin matrices were Newtonian fluid regardless of diluent concentration and all experimental composites exhibited pseudoplastic behavior with increasing shear rate. The viscosity of composites was exponentially increased with increasing filler volume%. In the same filler volume, the smaller the fillers were used, the higher the viscosities were. The effect of filler size on the viscosity was increased with increasing filler content. Increasing filler content reduced $tan{\delta}$ by increasing the G' further than the G". The viscosity of composites was decreased exponentially with increasing temperature.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.25 no.2
• /
• pp.259-267
• /
• 1998

For more than two decades, many investigators have tried a variety of methods for delivering antimicrobial agents to the oral cavity with the objective of eliminating mutans streptococci. In the belief that the effectiveness of chemotherapy might be improved by a more effective delivery system, the intention of the present study was to exploit a new drug delivery system delivering chlorhexidine to the oral cavity. The vehicle delivering chlorhexidine tested in this study was self-curing acrylic resin(polymethyl methacrylate). The powder of the acrylic resin was polymerized with the 5 different liquid preparations, in which $Chlorzoin^{(R)}$ was mixed with five different monomer/Chlorzoin ratios immediately prior to the polymerization, in a stainless steel mold ($40mm{\times}40mm{\times}2mm$). A total of 50 cured resin specimens were divided into 5 groups according to the different monomer preparations. Every specimen was soaked in an airtight container filled with distilled water (100 ml) and then kept in an incubator at $37^{\circ}C$. The solutions (0.8 ml) were collected from the container at every 24 hours, and the amount of released chlorhexidine in the solutions was measured in an ultraviolet spectrophotometer at 250nm. The container was refilled with distilled water every after measurement. This procedure was repeated for 14 days. It was found that chlorhexidine was continuously released from all of the 50 specimens during the experimental period. And it was noted that the pattern of chlorhexidine release was a type of sustained-release preparation, that is, the amount of the released chlorhexidine at the first day in all 5 groups was high (p<0.0001), and then the release was decreased during the rest of the experimental period (p<0.001).

• Clean Technology
• /
• v.13 no.3
• /
• pp.208-214
• /
• 2007

Environmentally-friendly acrylic resin particles having the diameter between $0.1\;and\;1\;{\mu}m$ were prepared using non-aqueous dispersion (NAD) polymerization technique. The first step is to prepare the stabilizer and the next step is the NAD polymerization by dropping an acrylic monomer to stabilizer dispersed in organic media. To obtain a NAD resin with proper level of viscosity, it fumed out that stabilizers having sufficient viscosity such as 1000 cP need to be used, for which the stepwise feeding of monomer and initiator was necessary. It was necessary to put proper amount of stabilizer, but no more increase in viscosity was observed when more than that amount of stabilizer was added. Choice of proper monomers considering solubility parameter was essential to avoid the bimodal particle size distribution in the NAD resin product.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.18 no.1
• /
• pp.13-24
• /
• 2000

UV-curable resin has the properties of quick-drying, high productivity at low temperature, energy, space saving, solventless, non-polluting and low-stinking, and thus, UV-curing system has been widely used in the fields of printing inks, adhesives, paints and coating agents. This study has been executed to develop a new functionnal material by the polymerization induced phase separation. The results obtained were as follows. As for the curing properties of the monomer/prepolymer/alkyd resin blends, it was found out that there was a peak by the polymerization induced phase separation when measuring the changes of viscosity and elasticity. It was also found out that such polymerization phase separation occurred in case that the alkyd resin contents were 20wt% and 30wt% and not found at the contents of 40wt%. Therefore, it would be desirable to maintain the contents of alkyd resin at less than 30wt% in order to use the polymerization induced phase separation.

• The Journal of Korean Academy of Prosthodontics
• /
• v.37 no.1
• /
• pp.42-50
• /
• 1999

This study investigated the effects of surface treatment for filling resins on the surface texture of denture resin teeth by the use of scanning electron microscope. This study also evaluated the bond strength of filling resins to denture resin teeth. The denture resin teeth in this study was Endura Posterio(Shofu Co., Japan). The ailing resins used were Coe-cure(Coe Co., USA), Vertex RS (Dentimax Ziest, Holland), and light cured resin Z-100(3M Co., USA). The test sample were divided into 3 parts. Group 1 : Sandblasted with $50{\mu}m$ Aluminum oxide. Group 2 : Treated with #60 silicone carbide paper Group 3 : Treated with monomer brush application. Control Group : No Treatment. The results were as follows ; 1. The bond strength of filling resins to denture resin teeth is increased by surface treatment. 2. Regardless of the filling resins, there was a significant difference with # 60 silicone carbide paper treated group. 3. Regardless of each group, the bond strength according to the filling resins were decreased in the following order: Vertex RS, Coe-cure and Z-100.